Buggy code:
public final class SafeStylesUtils { static class Impl { public SafeStyles forOpacity ( double value ) { } } static class ImplServer extends SafeStylesUtils . Impl { private SafeStylesUtils . ImplIE6To8 implIE = new SafeStylesUtils . ImplIE6To8 ( ) ; @ Override public SafeStyles forOpacity ( double value ) { } } static class ImplIE6To8 extends SafeStylesUtils . Impl { @ Override public SafeStyles forOpacity ( double value ) { } } private static SafeStylesUtils . Impl impl ; public static SafeStyles forBackgroundImage ( SafeUri uri ) { } public static SafeStyles forBorderStyle ( BorderStyle value ) { } public static SafeStyles forBorderWidth ( double value , Unit unit ) { } public static SafeStyles forBottom ( double value , Unit unit ) { } public static SafeStyles forCursor ( Cursor value ) { } public static SafeStyles forDisplay ( Display value ) { } public static SafeStyles forFloat ( Float value ) { } public static SafeStyles forFontSize ( double value , Unit unit ) { } public static SafeStyles forFontStyle ( FontStyle value ) { } public static SafeStyles forFontWeight ( FontWeight value ) { } public static SafeStyles forHeight ( double value , Unit unit ) { } public static SafeStyles forLeft ( double value , Unit unit ) { } public static SafeStyles forLineHeight ( double value , Unit unit ) { } public static SafeStyles forListStyleType ( ListStyleType value ) { } public static SafeStyles forMargin ( double value , Unit unit ) { } public static SafeStyles forMarginBottom ( double value , Unit unit ) { } public static SafeStyles forMarginLeft ( double value , Unit unit ) { } public static SafeStyles forMarginRight ( double value , Unit unit ) { } public static SafeStyles forMarginTop ( double value , Unit unit ) { } public static SafeStyles forOpacity ( double value ) { } public static SafeStyles forOutlineStyle ( OutlineStyle value ) { } public static SafeStyles forOutlineWidth ( double value , Unit unit ) { } public static SafeStyles forOverflow ( Overflow value ) { } public static SafeStyles forOverflowX ( Overflow value ) { } public static SafeStyles forOverflowY ( Overflow value ) { } public static SafeStyles forPadding ( double value , Unit unit ) { } public static SafeStyles forPaddingBottom ( double value , Unit unit ) { } public static SafeStyles forPaddingLeft ( double value , Unit unit ) { } public static SafeStyles forPaddingRight ( double value , Unit unit ) { } public static SafeStyles forPaddingTop ( double value , Unit unit ) { } public static SafeStyles forPosition ( Position value ) { } public static SafeStyles forRight ( double value , Unit unit ) { } public static SafeStyles forTableLayout ( TableLayout value ) { } public static SafeStyles forTextDecoration ( TextDecoration value ) { } public static SafeStyles forTop ( double value , Unit unit ) { } public static SafeStyles forTrustedBackgroundColor ( String value ) { } public static SafeStyles forTrustedBackgroundImage ( String value ) { } public static SafeStyles forTrustedBorderColor ( String value ) { } public static SafeStyles forTrustedColor ( String value ) { } public static SafeStyles forTrustedOutlineColor ( String value ) { } public static SafeStyles forVerticalAlign ( double value , Unit unit ) { } public static SafeStyles forVerticalAlign ( VerticalAlign value ) { } public static SafeStyles forVisibility ( Visibility value ) { } public static SafeStyles forWidth ( double value , Unit unit ) { } public static SafeStyles forZIndex ( int value ) { <START_BUG> return new SafeStylesString ( ( ( "zIndex:<seq2seq4repair_space>" + value ) + ";" ) ) ; <END_BUG> } public static SafeStyles fromTrustedNameAndValue ( String name , double value , Unit unit ) { } public static SafeStyles fromTrustedNameAndValue ( String name , String value ) { } public static SafeStyles fromTrustedString ( String s ) { } static void verifySafeStylesConstraints ( String styles ) { } private static SafeStylesUtils . Impl impl ( ) { } private SafeStylesUtils ( ) { } }

Fix:
return new SafeStylesString ( ( ( "z-index:<seq2seq4repair_space>" + value ) + ";" ) ) ;